I prefer cialis for the (much) longer halflife. Personally I didn't find any difference in erection quality but i see a lot of people saying they get much harder from it.
I do tend to get stiff/sore upper back/shoulders from cialis but less flushing/stuffiness than viagra. Levitra I found pretty much the same as viagra. Reflux can be an issue for me with any of them but I have a hiatus hernia so that doesn't help.
Plus I can't remember which one, it's viagra or levitra you also have to consider when/what you've eaten whereas cialis you don't.
Some people seem to do combo's. Take the cialis whenever the day or two prior then viagra/levitra pre-sex. Caution though when mixing, wouldn't do it if you haven't gotten to know how they effect you 1st and also be careful with titrating the dose, start with the minimum dosage